1. Technical Field
The present disclosure relates to a display device displaying pictures.
2. Description of the Related Art
A display device displays pictures, utilizing voltages applied between gate lines and source lines. Defects in source lines, gate lines or color filter remarkably deteriorate the displayed pictures.
In order to inspect the source lines or the gate lines, an inspection signal is transmitted to the source lines and the gate lines. In accordance with the transmission of the inspection signal, a white image or a monochromatic (red, green, or blue) image is displayed on a display surface where the gate lines and the source lines intersect with each other. For example, an inspector can observe an image projected on the display surface to detect a fault of the display device.
For example, the inspector can observe the white image to detect a defect of the source lines or the gate lines. Moreover, the inspector can observe a red, green, or blue image to detect a defect of the color filter. The above-described inspection is preferably performed under a condition close to actual use. Accordingly, preferably, in an inspection process as well, the inspection signal of a high frequency is input to the source lines or the gate lines similarly to a video signal to actually display pictures.
From the viewpoint of observation of the pictures, the display device preferably has a wide display surface. On the other hand, from the viewpoint of portability of the display device, the display device is desirably small. In many cases, the display device is designed to narrow a frame portion surrounding the display surface in accordance with the planned use of the device.
The prior art discloses three conductive bands to transmit the inspection signal to the source lines. The three conductive bands are arrayed along a surface of a substrate. In order to satisfy the above-described needs, the three conductive bands used for the inspection are preferably cut off from the display surface after the inspection of the display device. However, the removal of the conductive bands increases manufacturing processes of the display device. Accordingly, the conductive bands used for the inspection may be incorporated into the display device (See Japanese Unexamined Patent Application Publication No. JP 2006-243706).
In many cases, the conductive bands used for the inspection are formed on sides of the display surface where the source lines and the gate lines intersect with each other. The conductive bands incorporated in the display device are contained in the frame portion surrounding the display surface.
Design of the narrow frame portion requires narrow conductive bands. As a result, resistance values of the conductive bands will be increased. The high resistance values of the conductive bands make it difficult to input the inspection signal of a high frequency to the source lines or the gate lines. As a result, accuracy of the inspection of the display device will decrease.